The present invention relates to electrical switches of a type mounted to a bracket or panel, and having an actuating plunger extending therethrough for being contacted by a user-movable member for effecting movement of the plunger, and actuation and deactuation of the switch. Switches of this type are typically employed for the brake light or stop lamp switch in motor vehicles where the plunger is held depressed by the vehicle's service brake pedal arm; and, the plunger is released upon movement of the brake pedal arm by the vehicle driver, causing a switch to energize the vehicle stop or brake lights.
In providing plunger actuated brake light switches for automotive vehicles, problems have been encountered in mounting the switch assembly for actuation by the vehicle brake pedal arm inasmuch as the at-rest, or unactuated position of the brake pedal arm is extremely difficult to predetermine with any degree of precision because the brake pedal is spring loaded against a resilient, typically elastomeric, limit stop. Thus, although the brake light switch assembly may be accurately located on a mounting bracket positioned adjacent the brake pedal arm, the variation from vehicle to vehicle in the position of the brake pedal arm at rest with respect to the switch mounting bracket requires that each brake light switch be adjustably mounted in order to permit calibration of the actuating point in the movement of the brake light switch plunger with respect to the at rest position of the brake pedal arm.
It has thus been desired to find a way or means of providing for mounting in mass production a plunger-actuated switch assembly for mounting with respect to a user-actuated member which has a variable at-rest position from assembly to assembly. In particular, it has been desired to find a way or means of positioning a vehicle brake light switch adjacent the brake pedal arm in a manner which eliminates the need to calibrate the mounting position of each vehicle switch with respect to the brake pedal arm at rest position for proper actuation of the switch plunger.
In a known plunger actuated switch employed in vehicles for switching on interior lights upon door opening, where the plunger is moved by the door frame, as described in FIGS. 1 and 2, a switch housing portion 10 has the movable plunger 12 extending therefrom with a plurality of ribs or convolutions 14 provided on the housing. A collar 16 is received over the housing, and has a rib 18 which engages the convolutions for permitting adjustable positioning of the collar on the housing.
The collar has an annular detent surface 18 provided about the outer surface thereof, and a movable annular locking member 20 received thereover and axially movable thereon. The locking member 20 has a plurality of circumferentially spaced axially extending curved fingers 22 provided thereon, which are radially deformable by the outer periphery of the collar 16 upon sliding movement of the locking member 20 with respect to the collar 16. In FIG. 1, the assembly is shown with the locking member 20 moved axially to the upwardmost position on the collar 16, wherein the fingers 22 move radially inwardly against the collar 16 by virtue of self-bias, thereby enabling the assembly to be inserted in an aperture 24 provided in a suitable mounting structure 26. In FIG. 2, the assembly is shown after installation, with the housing 12 and collar 16 moved upward, thereby camming the fingers 22 radially outwardly until an annular locking member is registered against the mounting structure 26; whereupon, the fingers 22 snap radially inwardly to engage the detent surface 18, thereby securing the assembly onto the mounting structure 26, as a result of the radially outward spreading of the fingers 22 over the aperture 24. In the application of the switch shown in FIGS. 1 and 2, the actuation point of the switch is not important, so long as the door movement is sufficient to permit the plunger to travel its full-stroke to effect switch actuation: thus, the mounting of the switch is not critical with respect to the door frame position.
It has, therefore, been desired to find a convenient way or means of rigidly mounting a plunger operated electrical switch on an apertured structure in high volume mass production for actuation by a user moveable member and to provide precise control of the switch actuation despite variation in the position of moveable member with respect to the mounting structure from one assembly to the next without requiring an adjustable switch mounting.